Non-line-of-sight 300 GHz band wireless link enabled by a frequency dependent reflective surface

Reconfigurable intelligent surface is a promising technology for the up-coming sixth-generation (6G) of cellular communication networks. In this context, an experimental study of specular and nonspecular reflections of a reflective surface (RS) by scattering parameter measurements in the 300 GHz range is presented. Here, we compare the insertion loss of a fixed and passive RS at its optimal output deflection angle with respect to the specular reflection on a metallic plate. We propose a methodology to assess the losses induced by the surface and validate the use of the device within a THz link. At its best, around 290 GHz, the surface insertion loss is less than 3 dB compared to the metallic plate. We then investigate a non-line-of-sight (LoS) THz link operating in QSPK and QAM-16 coherent transmission using the RS. Data rates up to 10 Gbits/s for QSPK and 20 Gbits/s for QAM-16 are obtained. This is, to the best authors knowledge, the first demonstration of a NLoS THz data-link including such RS.